Social authentication essentially means using the “Log in with x” button in your application, where “x” is a Social Login Provider of some kind. The Social Login Providers currently supported by Stormpath are:
Social Directories are a kind of mirrored Directory, in that they are used to mirror user information found in an external database. This means that entities like Groups can only exist in a your Stormpath Social Directory if they are mirrored in from the external Social provider.
Please read our How Social Authentication Works chapter in our product documentation.
Also, you can learn more about social login with these language- and social-specific resources: